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    <title>ShellCheck: SC1040 – When using `<<-`, you can only indent with tabs.</title>
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    <h1>SC1040 – ShellCheck Wiki</h1>
    <a href="https://github.com/koalaman/shellcheck/wiki/SC1040">See this page on GitHub</a>
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    <h2 id="when-using---you-can-only-indent-with-tabs">When using
<code>&lt;&lt;-</code>, you can only indent with tabs.</h2>
<h3 id="problematic-code">Problematic code:</h3>
<p>Any code using <code>&lt;&lt;-</code> that is indented with spaces.
<code>cat -T script</code> shows</p>
<div class="sourceCode" id="cb1"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb1-1"><a href="SC1040.html#cb1-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cat</span> <span class="op">&lt;&lt;- foo</span></span>
<span id="cb1-2"><a href="SC1040.html#cb1-2" aria-hidden="true" tabindex="-1"></a><span class="st">        Hello world</span></span>
<span id="cb1-3"><a href="SC1040.html#cb1-3" aria-hidden="true" tabindex="-1"></a><span class="st">    foo</span></span></code></pre></div>
<h3 id="correct-code">Correct code:</h3>
<p>Code using <code>&lt;&lt;-</code> must be indented with tabs.
<code>cat -T script</code> shows</p>
<div class="sourceCode" id="cb2"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb2-1"><a href="SC1040.html#cb2-1" aria-hidden="true" tabindex="-1"></a><span class="ex">^Icat</span> <span class="op">&lt;&lt;- foo</span></span>
<span id="cb2-2"><a href="SC1040.html#cb2-2" aria-hidden="true" tabindex="-1"></a><span class="st">^I^IHello world</span></span>
<span id="cb2-3"><a href="SC1040.html#cb2-3" aria-hidden="true" tabindex="-1"></a><span class="st">^Ifoo</span></span></code></pre></div>
<p>Or simply don't indent the end token:</p>
<div class="sourceCode" id="cb3"><pre class="sourceCode sh"><code class="sourceCode bash"><span id="cb3-1"><a href="SC1040.html#cb3-1" aria-hidden="true" tabindex="-1"></a>    <span class="fu">cat</span> <span class="op">&lt;&lt;- foo</span></span>
<span id="cb3-2"><a href="SC1040.html#cb3-2" aria-hidden="true" tabindex="-1"></a><span class="st">      Hello World</span></span>
<span id="cb3-3"><a href="SC1040.html#cb3-3" aria-hidden="true" tabindex="-1"></a><span class="op">foo</span></span></code></pre></div>
<h3 id="rationale">Rationale:</h3>
<p><code>&lt;&lt;-</code>, by design, only strips tabs. Not spaces.</p>
<p>Your editor may be automatically replacing tabs with spaces, either
when you type them or when you save the file or both. If you're unable
to make it stop, just don't indent the end token.</p>
<h3 id="exceptions">Exceptions</h3>
<p>None. But note that copy-pasting code to <a
href="../index.html">shellcheck.net</a> may also turn
correct tabs into spaces on some OS.</p>
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    <p style='font-size: 80%'><a href="../index.html">ShellCheck</a> is a static analysis tool for shell scripts. This page is part of its documentation.</p>
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